1. Field of the Invention
The present invention relates to eyeglasses having lenses wherein a portion of each lens includes an element that reduces the intensity of polarized light passing therethrough.
2. Prior Art
Polarized glasses, i.e., spectacles comprised of a pair of lenses that at least partially blocks the intensity of polarized light passing therethrough, are well known in the art for reducing glare from reflected light. In such polarizing lenses, a sheet polarizer is coextensive with substantially the entire lens. A “sheet polarizer” of the type referred to above is a polymeric film used for producing polarized light from unpolarized light. An example of a sheet polarizer that is commonly used for producing polarized light is a stretched sheet of a colorless polymeric film treated with an iodine solution. The most commonly used polarizer sheet includes a plurality of chains of polymer molecules such as, for example, polyvinyl alcohol (PVA), wherein each of the PVA polymer chains has a long axis, or “polarizer axis”, which is parallel to the long axis of all other PVA chains, and containing conductive iodine atoms.
If a sheet polarizer is incorporated into a lens such as, for example, by stretching a PVA film over an optically transparent (or tinted) lens during the molding process, wherein the long axis of the sheet polarizer (i.e., the polarizer axis) is vertically oriented when the lens is mounted in a frame, the sheet polarizer will substantially block the passage of horizontally polarized light therethrough, thereby reducing glare associated with light reflected from a horizontal surface (i.e., horizontally polarized light). While glare reduction is an advantage, such sheet polarizers also reduce the intensity of circularly polarized light passing therethrough which makes it difficult to see in a suddenly darkened environment. There is a need for eyeglasses that provide the glare reduction advantage of polarized lenses while retaining the ability to transmit substantially all of the light within a field of view to the pupil under reduced lighting conditions such as is encountered during night driving.